As is generally known, vaginal specula are used by physicians for dilating the opening of the vaginal cavity in order that the vaginal walls and cervix may be more easily visible and accessible for examination, diagnosis and treatment by surgery or otherwise.
Standard bivalve specula typically comprise two blades (an upper blade and a lower blade), joined near their proximal ends by a fixed hinge. At least one of the blades includes a handle, depending from the proximal end of the blade, for the physician to hold. The co-operating proximal end portions of the blades define a proximal aperture, through which aperture the physician may observe and access the vaginal cavity and cervix with instruments for inspection, investigation or surgery. Commonly the handle comprises two operating levers that can be moved relative to one another to open or close the blades.
In use, the speculum is positioned in the vaginal canal so that the upper blade is adjacent the top of the vaginal canal and the lower blade is adjacent the bottom of the vaginal canal. The blades are then splayed apart by operation of the levers to dilate the vaginal canal by pressing apart its top and bottom. In view of the fixed hinge, the dilation of the vaginal canal is greatest at the distal ends of the blades and decreases towards their proximal ends.
Typically, specula are also provided with a locking mechanism for locking the blades in position against vaginal wall muscle contraction once opened to a desired extent. A typical locking mechanism comprises a threaded rod joined by a pivot to one operating lever and a nut in threaded engagement with the rod and which can be tightened against the other operating lever. It will be appreciated that locking the position of the open blades requires both hands and can be an awkward manoeuvre.
Although the bivalve speculum is effective in widening the cervical end of the vaginal canal by splaying apart the blades, the access to the vaginal canal is determined by the diameter of the introitus of the vagina, and hence by the proximal aperture which normally cannot be widened any further. It will be appreciated that better access may be required during some treatments such as surgical procedures or in order to use certain medical instruments.
Accordingly, mobile-hinged specula, such as Graves' speculum, exist in which the upper and lower blades are not directly joined together so that the upper blade and the lower blade can be moved apart without the distal ends of the blades splaying apart. However, although this is a more adaptable speculum than the conventional fixed-hinge type, it is more complicated and more time-consuming to operate because the blade separation, blade flaring and locking operations all involve separate actions and are difficult or impossible to perform with one hand. This protracted routine is also not desirable from the point of view of the patient who would prefer the examination or treatment to be quick and to require generally less manipulation of the speculum.
A further problem associated with most speculum designs is that the handle or handles of the specula are normally at an acute angle, or at a right angle, to the blades. This inevitably results in the physician's hands and fingers being in contact with, or in close proximity to, the patient's genitalia, upper thighs and buttocks during a gynaecological procedure, which may be distressing to the patient and lead to accusations of impropriety against the physician.
Known speculum designs are ineffective in the case of patients having lax vaginal walls which prolapse and protrude inwardly between the open blades of the speculum in use, thus obstructing the physician's view and access and hindering procedures such as cervical smear-taking and treatment such as electrosurgery.
To overcome vaginal side wall prolapse, four-bladed specula are known in the art in which two additional blades are provided for supporting and pressing back the vaginal side walls during examination and treatment. Specula of this type are described in U.S. Pat. No. 5,868,668 and U.S. Pat. No. 6,024,696. In some cases, however, the additional blades must be manually operated by the physician when the speculum is in position, in addition to operation of the upper and lower blades as aforesaid. This inevitably requires the use and co-ordination of both hands which is cumbersome and awkward for the physician and also delays the procedure while both hands of the physician are occupied in operating the speculum. It is also unpleasant for the patient who may feel both of the physician's hands come into contact with, or be in proximity to, her genitalia, upper thighs and buttocks.
These problems have been partially overcome by the applicant's earlier invention as disclosed in WO 00/69325, which describes a speculum having two blades joined near their proximal ends by a floating hinge or pivot which allows the blades to move apart to widen the proximal opening without the blades necessarily splaying apart. Advantageously, the speculum includes an operating mechanism which allows one-handed operation. Also described are supplementary blades attached to the lower blade whose lateral splaying can also be controlled with one hand. Further, the operating lever and handle are obtusely angled in a proximal direction with reference to the blades so that the physician's hands and fingers are spaced further away from the patient's body when operating the speculum.
Although the floating hinge allows some widening of the proximal opening and therefore access into the vaginal cavity, this widening is limited by the length of the floating hinge itself and so this speculum is still not appropriate for use with some surgical procedures where a yet wider access is required into the vaginal cavity.
Additionally, the supplementary blades and associated parts make it difficult to clean and sterilise the instrument. This is especially pertinent in light of the current fear of MRSA ‘super-bug’ infections in hospitals and clinics. To combat the spread of MRSA, it is now policy in most if not all hospitals to dispose of medical instruments after single use unless their construction allows for effective cleaning and sterilisation. Undoubtedly, this would mean that the speculum described in WO 00/69325, as well as other similar prior art instruments such as those disclosed in U.S. Pat. No. 6,048,308 and WO 99/12466, would be treated as single-use instruments because of their construction and so disposed of after one use. However, the cost of manufacture of these complex instruments can be high. In addition, the design of such specula can necessitate the use of metals, with the associated fabrication and material costs being higher than if plastics could be used. It is apparent that the resulting wastage, both in terms of costs and materials, is significant. If instruments are to be disposable, one use only, they need to be as simple and inexpensive as possible but without losing functionality.